We’ve mentioned the possibility of seeing, sooner or later, Windows Phone 7 certified memory cards with all the buzz around this issue and even AT&T is telling its Windows Phone 7 subscribers that are device owners — read Focus — to hold back until certified cards will be available.

Microsoft has published a knowledge base article entitled Windows Phone 7 Secure Digital Card Limitations (Revision 5.1 as of November 9) which doesn’t clarify the issue to the extent most of us wanted or expected. While talking about some Windows Phone 7 handsets that might come with a memory slot, the article states clearly that it is not for you to tamper with as “the SD card slot in your phone is intended to be used only by the Original Equipment Manufacturer (OEM) that built your phone and your Mobile Operator (MO). These partners can add an SD card to this slot to expand the amount of storage on your phone”. Removing or replacing the included card could render your device inoperable and can also lead to data loss. Even more, the article clearly states that if your device features an easily accessible card slot, like the Samsung Focus, you should consider it an unmovable hardware part and permanent component of your phone!

“To help ensure a great user experience, Microsoft has performed exhaustive testing to determine which SD cards perform well with Windows Phone 7 devices. Microsoft has worked closely with OEMs and MOs to ensure that they only add these cards to Windows Phone 7 devices”. Even though memory cards “must meet certain performance requirements for the phone to function optimally”, the article doesn’t mention any of the criteria that would help someone identify a card as safe-to use, because, as stated above, you should simply not touch it according to Microsoft. If you were thinking, even for a second, that card speed class matters, you might be right, but it’s not the only criteria to take into consideration: “determining whether an SD card is Windows Phone 7 compliant is not a simple matter of judging its speed class. Several other factors, such as the number of random read/write operations per second, play a role in determining how well an SD card performs with Windows Phone 7 devices”.

To read the rest of the KB article, head over to the source link and make sure to leave us your comments below on both the fact that Microsoft wants you to treat your removable memory card as a permanent, non-removable hardware component as well as on judgment regarding performance requirements.